1. Technical Field of the Invention
The present invention relates to an electro-optic device and an electronic instrument, and more specifically, it relates to a structure mounted on a circuit board disposed in the electronic instrument and suitable for the electro-optic device.
2. Description of the Related Art
In general, comparative small-sized liquid crystal display modules are used for the display of portable electronic instruments such as mobile phones and various electronic instruments. Such a liquid crystal module is generally mounted on a circuit board disposed within the instrument in a conductive contact state. The liquid crystal module includes a liquid crystal panel, a backlight disposed in the rear of the liquid crystal panel and including a light-guide plate, a flexible wiring substrate conductively connected to the liquid crystal panel, and a holding case (holding-frame member) for holding the liquid crystal panel, the backlight, and the flexible wiring substrate.
There is a structure for mounting the above-mentioned liquid crystal module on the circuit board, in which exposed conductive pad-like substrate terminals (contact terminals) are formed on the flexible wiring substrate in the liquid crystal module, and the holding case is fixed on the circuit board so that the substrate terminals are directly brought into conductive contact with elastic terminals of a connector mounted on the circuit board, respectively. In this case, the holding case is held with a holding frame abutting thereon from an observing side of the liquid crystal panel, and the holding frame is fixed onto the circuit board. The holding case may also be directly fixed onto the circuit board by engaging a hook.
In the conventional mounting structure of the liquid crystal module described above, a contact pressure between the substrate terminals of the liquid crystal module and connector terminals on the circuit board must be appropriately established. If the contact pressure is excessively small, for example, the conductive contact state between the liquid crystal module and the circuit board is deteriorated so that the liquid crystal module operation may become unstable or the display quality is degraded by the contact resistance. Also, if the contact pressure is excessively large, the pressure may be applied to the liquid crystal panel via the light-guide plate of the liquid crystal module, thereby producing display unevenness due to the nonuniformity of the liquid crystal panel gap (thickness of liquid crystal).
However, in the conventional mounting structure of the liquid crystal module described above, because of allowable errors in the holding case of the liquid crystal module, the holding frame or the holding structure for fixing the holding case, and the connector of the circuit board, the contact pressure cannot be precisely estimated in advance, so that sizes are adjusted so as to obtain the appropriate contact pressure by correcting a metal mold for the holding case after assembling parts once manufactured. Therefore, there are problems that the design and development cycle required for supplying the liquid crystal module to a market is increased while initial costs necessary for initiating mass production are increased.
The present invention has been made to solve the problems described above, and it is an object thereof to provide an electro-optic device and an electronic instrument having the electro-optic device capable of completing the development design without correcting part shapes so as to be promptly supplied to market.
Also, it is another object thereof to provide an electro-optic device and an electronic instrument having the electro-optic device capable of reducing initial costs as a consequence of the design and development compared to the conventional case.